[Qemu-devel] [PATCH COLO-Frame v10 02/38] migration: Introduce capability 'x-colo' to migration

[zhanghailiang <zhang.zhanghailiang@huawei.com>]

We add helper function colo_supported() to indicate whether
colo is supported or not, with which we use to control whether or not
showing 'x-colo' string to users, they can use qmp command
'query-migrate-capabilities' or hmp command 'info migrate_capabilities'
to learn if colo is supported.

Cc: Juan Quintela <quintela@redhat.com>
Cc: Amit Shah <amit.shah@redhat.com>
Cc: Eric Blake <eblake@redhat.com>
Cc: Markus Armbruster <armbru@redhat.com>
Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>
Signed-off-by: Gonglei <arei.gonglei@huawei.com>
---
v10:
- Rename capability 'colo' to experimental 'x-colo' (Eric's suggestion).
- Rename migrate_enable_colo() to migrate_colo_enabled() (Eric's suggestion).
---
 include/migration/colo.h      | 20 ++++++++++++++++++++
 include/migration/migration.h |  1 +
 migration/Makefile.objs       |  1 +
 migration/colo.c              | 18 ++++++++++++++++++
 migration/migration.c         | 17 +++++++++++++++++
 qapi-schema.json              |  6 +++++-
 qmp-commands.hx               |  1 +
 stubs/Makefile.objs           |  1 +
 stubs/migration-colo.c        | 18 ++++++++++++++++++
 9 files changed, 82 insertions(+), 1 deletion(-)
 create mode 100644 include/migration/colo.h
 create mode 100644 migration/colo.c
 create mode 100644 stubs/migration-colo.c

diff --git a/include/migration/colo.h b/include/migration/colo.h
new file mode 100644
index 0000000..c60a590
--- /dev/null
+++ b/include/migration/colo.h
@@ -0,0 +1,20 @@
+/*
+ * COarse-grain LOck-stepping Virtual Machines for Non-stop Service (COLO)
+ * (a.k.a. Fault Tolerance or Continuous Replication)
+ *
+ * Copyright (c) 2015 HUAWEI TECHNOLOGIES CO., LTD.
+ * Copyright (c) 2015 FUJITSU LIMITED
+ * Copyright (c) 2015 Intel Corporation
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or
+ * later.  See the COPYING file in the top-level directory.
+ */
+
+#ifndef QEMU_COLO_H
+#define QEMU_COLO_H
+
+#include "qemu-common.h"
+
+bool colo_supported(void);
+
+#endif
diff --git a/include/migration/migration.h b/include/migration/migration.h
index 8334621..8643a74 100644
--- a/include/migration/migration.h
+++ b/include/migration/migration.h
@@ -170,6 +170,7 @@ int xbzrle_decode_buffer(uint8_t *src, int slen, uint8_t *dst, int dlen);
 
 int migrate_use_xbzrle(void);
 int64_t migrate_xbzrle_cache_size(void);
+bool migrate_colo_enabled(void);
 
 int64_t xbzrle_cache_resize(int64_t new_size);
 
diff --git a/migration/Makefile.objs b/migration/Makefile.objs
index d929e96..5a25d39 100644
--- a/migration/Makefile.objs
+++ b/migration/Makefile.objs
@@ -1,4 +1,5 @@
 common-obj-y += migration.o tcp.o
+common-obj-$(CONFIG_COLO) += colo.o
 common-obj-y += vmstate.o
 common-obj-y += qemu-file.o qemu-file-buf.o qemu-file-unix.o qemu-file-stdio.o
 common-obj-y += xbzrle.o
diff --git a/migration/colo.c b/migration/colo.c
new file mode 100644
index 0000000..2c40d2e
--- /dev/null
+++ b/migration/colo.c
@@ -0,0 +1,18 @@
+/*
+ * COarse-grain LOck-stepping Virtual Machines for Non-stop Service (COLO)
+ * (a.k.a. Fault Tolerance or Continuous Replication)
+ *
+ * Copyright (c) 2015 HUAWEI TECHNOLOGIES CO., LTD.
+ * Copyright (c) 2015 FUJITSU LIMITED
+ * Copyright (c) 2015 Intel Corporation
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or
+ * later.  See the COPYING file in the top-level directory.
+ */
+
+#include "migration/colo.h"
+
+bool colo_supported(void)
+{
+    return true;
+}
diff --git a/migration/migration.c b/migration/migration.c
index b092f38..0d7068f 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -30,6 +30,7 @@
 #include "qapi/util.h"
 #include "qapi-event.h"
 #include "qom/cpu.h"
+#include "migration/colo.h"
 
 #define MAX_THROTTLE  (32 << 20)      /* Migration transfer speed throttling */
 
@@ -364,6 +365,9 @@ MigrationCapabilityStatusList *qmp_query_migrate_capabilities(Error **errp)
 
     caps = NULL; /* silence compiler warning */
     for (i = 0; i < MIGRATION_CAPABILITY_MAX; i++) {
+        if (i == MIGRATION_CAPABILITY_X_COLO && !colo_supported()) {
+            continue;
+        }
         if (head == NULL) {
             head = g_malloc0(sizeof(*caps));
             caps = head;
@@ -513,6 +517,13 @@ void qmp_migrate_set_capabilities(MigrationCapabilityStatusList *params,
     }
 
     for (cap = params; cap; cap = cap->next) {
+        if (cap->value->capability == MIGRATION_CAPABILITY_X_COLO &&
+            !colo_supported()) {
+            error_setg(errp, "COLO is not currently supported, please"
+                             " configure with --enable-colo option in order to"
+                             " support COLO feature");
+            continue;
+        }
         s->enabled_capabilities[cap->value->capability] = cap->value->state;
     }
 }
@@ -1018,6 +1029,12 @@ fail:
     migrate_set_state(s, MIGRATION_STATUS_ACTIVE, MIGRATION_STATUS_FAILED);
 }
 
+bool migrate_colo_enabled(void)
+{
+    MigrationState *s = migrate_get_current();
+    return s->enabled_capabilities[MIGRATION_CAPABILITY_X_COLO];
+}
+
 /* migration thread support */
 
 static void *migration_thread(void *opaque)
diff --git a/qapi-schema.json b/qapi-schema.json
index 7f0c4c5..cb5e5fd 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -540,11 +540,15 @@
 # @auto-converge: If enabled, QEMU will automatically throttle down the guest
 #          to speed up convergence of RAM migration. (since 1.6)
 #
+# @x-colo: If enabled, migration will never end, and the state of the VM on the
+#        primary side will be migrated continuously to the VM on secondary
+#        side. (since 2.5)
+#
 # Since: 1.2
 ##
 { 'enum': 'MigrationCapability',
   'data': ['xbzrle', 'rdma-pin-all', 'auto-converge', 'zero-blocks',
-           'compress', 'events'] }
+           'compress', 'events', 'x-colo'] }
 
 ##
 # @MigrationCapabilityStatus
diff --git a/qmp-commands.hx b/qmp-commands.hx
index 0eb92d7..2f885b3 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -3498,6 +3498,7 @@ Query current migration capabilities
          - "rdma-pin-all" : RDMA Pin Page state (json-bool)
          - "auto-converge" : Auto Converge state (json-bool)
          - "zero-blocks" : Zero Blocks state (json-bool)
+         - "x-colo" : COarse-Grain LOck Stepping for Non-stop Service (json-bool)
 
 Arguments:
 
diff --git a/stubs/Makefile.objs b/stubs/Makefile.objs
index 251443b..d3306c5 100644
--- a/stubs/Makefile.objs
+++ b/stubs/Makefile.objs
@@ -35,3 +35,4 @@ stub-obj-y += kvm.o
 stub-obj-y += qmp_pc_dimm_device_list.o
 stub-obj-y += target-monitor-defs.o
 stub-obj-y += vhost.o
+stub-obj-y += migration-colo.o
diff --git a/stubs/migration-colo.c b/stubs/migration-colo.c
new file mode 100644
index 0000000..3d817df
--- /dev/null
+++ b/stubs/migration-colo.c
@@ -0,0 +1,18 @@
+/*
+ * COarse-grain LOck-stepping Virtual Machines for Non-stop Service (COLO)
+ * (a.k.a. Fault Tolerance or Continuous Replication)
+ *
+ * Copyright (c) 2015 HUAWEI TECHNOLOGIES CO., LTD.
+ * Copyright (c) 2015 FUJITSU LIMITED
+ * Copyright (c) 2015 Intel Corporation
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or
+ * later.  See the COPYING file in the top-level directory.
+ */
+
+#include "migration/colo.h"
+
+bool colo_supported(void)
+{
+    return false;
+}
-- 
1.8.3.1